Impulse starting mechanism



'F. D. NORMN.

IMPULSE STARTING MECHAMSM. Armcmon mso strnzl. mr.

1 ,337,322. Patented A111. 20, 1920. l

2 IHEETS-SI'IEET l.

QA'. -ll M.. A VW.

F. n. NORMAN. IMPULSE STARTING MECHANISNI.

APLICATION FILED SEPT. 2l. 19|

Patented Apr. 20, 1920.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

FREDERICK BRAKE NORMAN. OF SPRINGFIELD, MASSACHUSETTS, ASSIGNOR. BY MESNE ASSIGNMENTS, T0 AMERICAN BOSCH MAGNETO CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

IMPULSE STARTING MECHANISM.

Application filed September 21, 1917.

v7b all wlan/n t may concern:

Be it known that I, Fimmnnol D. Non- MAN, a subject of the King of England, residing at Green Acres, Long Meadow, Springfield, in the county ofV Hampden, State of Massachusetts, have invented certain new and useful Improvements in Impulse Starting lllechanism; and l. do hereby declare the following to be a full, clear, and exact description of the invention, such as Will enable others skilled in the art to which it appertains to make and use the same,

The present invention relates to impulse starting` mechanism wherein the driven device is given one or more impulses, each for a .fraction of a turn. at a speed considerably higher' than the speed of the driving device, and it embodies the use of au impelling spring arranged to be stressed upon relative angular displacement of the driving and driven devices, of locking mechanism for locking the driven device against rotation while the driving device is rotating, and of releasing mechanism for releasing the driven device so that the spring, then stressed, impels the driven device through an appropriate angle. Such mechanism is applicable to various kinds of devices, such as prime movers which are not self-starting, and particularly to magnetos for generating ignition voltages suitable for iguitingg' gaseous mixtures present in the cylinder of the engine w'ith which it is associated when the engine is' beingr turned Aat low speed in starting.

In devices of this kind, it has been customary heretofore to provide mechanism for rendering the locking mechanism inoperative when the speed of the driving device exceeds predetermined value. In accordance with my invention, this predetermined value is made variable so that it is possible to adjust the speed at which the iml'iellinp,l movement ol" the driven member ceases, thus making it possible to use the same mechanism with engines stai-tin into action under their own ower at ditigerent speeds. [n the preferred orm of construction described hereinafter` this adjustable feature consists of (ne or more speed limiting or safety cams carried by the driven member at an ad- Specication of Letters Patent.

Patented A pr. 20. 1920.

serial No. 192,460.

justed position in advance of the locking mechanism.

My invention further comprehends improvements in construction applicable separately or in combination to impulse starting mechanisms which do or do not employ the features hereinbefore mentioned. In the preferred en'lbodiment hereinafter disclosed, a disk, mounted on the driving shaft and carrying angularly-adjlistahle releasing cams on its periphery, also carries cireulady-disposed coiled impelling and buffer springs abutting anchorage posts thereon, and pressure-applying members extending between the impelling and buffer springs project through slots in the fianged rim of the disk on the driven shaft into cooperation with a locking paivl. The parts on the driven shaft and the pressure-applying members are formed into a unitary structure by means of a retainingr ring threading the springs, the pressureapplying members and the posts.

In the accompanying drawings illustrating the preferred form of my impulse starting mechanism in application, as an example, to a magneto adapted to be driven by the internal combustion engine With which it is associated, Figure 1 is an elevation showing the impulse mechanism in section on line 1---1 of Fig. 2, and showing the magneto partly in section and partly in full view; Figs. 2 and 3 are sections on lines Q-2 and 3-3, respectively, of Fig. 1; Fig. f1 is a section on line 1w-4 of Fig. 3; and Fig. 5 is a section on line 5-5 of Fig. 2.

The magneto 1 is of a wel] known type having an armature 2, mechanical interrupter 3, collector 4, distributor 4', and .shaft 5. Th`e driving shaft 6 is su ported in a hearing T carried by a plate 8 orlmng the base-plate of the magneto, so as to support the driving shaft in alinement with the magneto shaft,- and it carries a pinion 9 adapted to he appropriately positioned and driven from the cam shaft of the internal combi-tion engine with which the magneto is associated for purposes of ignition.

The disk l0 is integral or otherwise fast with the drivingr shaft 6 and has on its face two diametrically-disposed anchorage posts 1l. The circularly-disposed coiled impelling springs l2 abut the anchorage posts, and the stifer and lshorter buffer springs 13 abut the other sides thereof. The diametrically disposed pressure appl fing members 14 extend between the impe ling and buffer springs. These parts are formed into a unitary structure by the retaining ring 15 loosely threading the syn-ings, the posts and the pressureapplying members. The retaining ring is split at 1G and its two ends are pinned after the 4parts are in place` The cam plate 17 is loosely journaled for adjustment. It has two slots 18 for adjusting its angular position, and the screws 19 fasten it in adjusted position on the disk 10. This plate 17 carries diametricallydisposed cams 20 extending over and outwardly of the periphery of the disk 10.

The disk 21 is fast on the magneto shaft 5 and has a flanged rim 22 and a pair of diametrically-disposed slots :23. rlhe pressure-appl ing members 14 project out wardly o the fianged rim .22 through the slots therein, and are bolted to the disk :21 at 24 to connect them thereto and to the driven shaft The speed limiting or Safety cams 25 are mounted on the outer periphery of the flanged rim 22 in advance of the respective pressure-applying members 14 in the direction of rotation, and are secured in adjusted position thereon by means of slots 26 and screws 27.

The pawl 28 is loosely journaled on the stud 29 carried by the stationary member 30. In its operative position, th'e pawl :28 rides on the outer peripheries of the lianged rim 22 and the disk 10, in position to be lifted by the safety cams 25 and the re leasing cams 20, and engaged by the projecting end of the pressure-appplying members 14. In its inoperative position, as shown in broken lines in Fig. 2. the pawl is supported by the arm 31 ou the other side of the stud 29.

The operation ot' the impulse starting mechanism will now be described, in connection with an internal combustion en gine to be fired by the magneto. The pawl 28 is brought to its operative position on the outer peripheries* of the disks 10 and 21 as shown in full lines in Fig. 2, and the drivingr shaft 6, connected to the crank shaft of the engine in properly timed relation, is turned by cranking the engine. The arrangement of the pawl and the pressure-applying members 14 is such that they engage to lock the magneto shaft against rotation,` just prior to the period of maxi mum generation of the magneto and the "interrupting action of the mechanical interrupter 3. Upon turning the drivin" shaft further, the impelling springs 12 are stressed, until finallv released by reason of engagement of a releasing cam 20 withV the paw] 28, the spring then being stressed suiciently to impel the magneto shaft Leemans throuvh an appropriate angle and at a sufficiently high speed to generate in the ma neto a satisfactory igniting voltage. t the end of this impelling movement, the buffer springs 13 arrest the magneto shaft without substantial shock or vibration. The stress of the impelling springs 12 and the coacting faces of the pawl and the [')ressure-applying members are such that the pawl is usually at the first instance thrown by the releasing cam to its inoperative position, so that if the engine should then start into action under its own power, as is usually the case, the magneto is thereafter driven directly by the engine. If, however, the engine should not start, the pawl is turned back as before into operative position and the operation repeated.

The angle by which the releasing cams 'lll normally trail thc pressure applying members in the direction of rotation, is made adjustable so that the relative angular displacements of the driving and driven shafts may be adjusted to provide at all times the requisite stress in the impelling springs at the instant of release. The driving shaft G is timed with the crank shaft of the engine by means of the pinon 9, in such mannerthat in their adjusted position the releasing cams lift the pawl to permit the magneto to be impelled and generate its sparking voltage at the time the piston to be fired thereby is at or near the beginning of its Working stroke. In the case of a multicylinder engine, the proper one of the cylinders to be fired is determined in the well known way by the distributor 4.

1f, upon starting of the engine, the 'pawl 28 should not be thrown into inoperative position, or if by inadvertence on the part of the operator, or through accident or for any other reason, the pawl should attain its operative position, it is, as a practical matter, prevented by the safety cams 25, from engaging the pressure-applying members 14 whenever the speed of the driving shaft exceeds a predetermined value, de pendent upon the angle by which the safety cams lead the projecting end of the pressure-applying members, the moment of inertia of the pawl, and other considerations, as will be readily understood. Thus, byA having the safety cams adjustable in angi' lar position on the disk 21, the speed of that driving shaft at which the locking mechanism is prevented from locking the driven member against rotation may be increased by increasing the lead of the safety cam, and

decreased by decreasing that angle. At low speed in starting, the pawl rides smoothly over the safety cams, but in excess of the 'mined value for contact With the outer peripheries of the disks and 21, the pressure-applying mem-- her has passed beyond its position of engagement with the pawl. At still higher speed, one or the other' of the safety cams throws the pavvl over its center' on the other side of the stud 29, whereupon it falls on to its support 31 in permanently inoperative position.

Although the impelling springs 12 are not in themselves strong enough to prevent substantial lag of the driven shaft during the' periods of maximum generation of the magneto, such lag is prevented during the running period of the engine when the locking mechanism is inoperative as a combined result of those springs and kinetic energy then stored in the rotating parts of the driven member. The disk 21 with its flanged rim 22 acts as a fly Wheel to materially assist in the attainment of this result.

Having thus described my invention, what l claim is:

l. In impulse starting mechanism, driving and driven "shafts, an impelling spring arranged to be stressed u'pon relative angular displacement of the shafts, locking mechanism for locking the driven shaft against rotation While the driving shaft is rotating, releasing mechanism for releasing the driven shaft, and angularly adjustable means carried by one of the shafts and cooperative with the locking mechanism to prevent locking of the driven shaft when the speed of the driving shaft exceeds the p1 detervvhich said adjustable means are set.

2. In impulse starting mechanism, driving and driven shafts, an impelling spring arranged to be stressed upon relative angular displacement of the shafts, locking mechanism for locking the driven shaft against rotation while the driving shaft is rotating` releasing mechanism for releasing the driven shaft, and an ularly adjustable means carried b the Criven shaft and coiperative with t e locking mechanism to prevent locking of the driven shaft when the speed of the driving shaft efceeds the predetermined value for which said adjustable means are set.

3. In impulse starting mechanism, driving and driven shafts, an impelling spring arranged to be stressed upon relative angular displacement of the shafts, locking mechanism for locking the driven shaft against rotation While the driving shaft is rotating, releasing mechanism for releasing the driven shaft, a. disk fast on one of said shafts, and a cam angularly adjustable on said disk and coperative with the locking mechanism to prevent locking of the driven shaft when the speed of the driving shaft exceeds the predetermined value for which the cam is set.

4. In impulse starting mechanism, driving and driven shafts, an impelling spring arranged to be stressed upon relative angulak` displacement ofthe shafts` locking mechanism for locking the driven shaft against rotation while the driving shaft is rotating, said locking mechanism including a member fast with the driven shaft, releasin mechanism for releasing the driven sha t, and a cam adjustable in angular position in advance of said member and coperative with the locking mechanism to prevent locking of the driven shaft when the speed of the driving shaft exceeds the predetermined value for which the cam yis set.

5. In impulse starting mechanism, driving and driven shafts, a member fast with the drivin shaft and having an anchorage post, a coi ed impelling spring abutting the post, a retaining member threading the spring and. engaging the post, mechanism constructed and arranged to lock the driven shaft against rotation .vhile the driving shaft is rotating and thereby stress the spring, and means for releasing the. driven shaft.

6. ln impulse starting mechanism, driving and driven shafts, a disk mounted on the driving shaftand having diametricallydisposed anchorage posts, a circularly-disposed coiled spring abutting the posts, a retaining ring threading the spring and the posts, mechanism constructed and arranged to lock the driven shaft against rotation while the driving shaft is rotating and 100 thereby stress the spring` and means for yreleasing the driven shaft.

7. In impulse starting mechanisnni driving and driven shafts, a member fast on the driving shaft and having an anchorage post, 105 circularly-disposed coiled and buffer springs abutting the post, a pressure-applying member extending between the impelling and buffer springs, a retaining ring threading said springs and member, mechanism con- 110 structed and arranged to lock the driven shaft and the pressure-applying member against rotation While the driving shaft is rotating, and means for releasing said mechanism from locking position.

S. In impulse starting mechanism, driving and driven shafts, a member fast on the driving shaft and having an anchorage post. circularly-disposed coiled impelling and buffer springs abutting the post, a pressures' 120 applying member extending between the inipelling and buffer springs `and connectd to the driven shaft` a retaining ring threading said springs and member, i' -chanism constructed and arranged to lock the driven 125 shaft against rotation while the driving shaft is rotating. and means for releasing said mechanism from locking position.

9. In impulse starting mechanism, driving and driven shafts, a disk mounted. on the 180 driving shaft and yhaving diametricallydisposed anchorage posts, circularly-disposed coiled impelling and bufferrsprings abutting the posts, iametrically-disposcd pressure-applying members extending between the impelling and buffer springs, a retaining ring threading the springs and members and engaging the posts, mechanism constructed and arranged to lock the driven shaft and the pressure-applying members against rotation While the driving shaft is rotating and thereby stress the impelling spring, and means for releasing said mechanism from locking position.

10. In impulse starting mechanism, driving and driven shafts, a disk mounted on the driving shaft and having diametrically-disposed anchorage posts, circularly-disposed coiled and impelling buffer springs abutting the posts, diametrically-disposed pressureapplying members extending between the impelling and buffer springs and connected to the driven shaft, a retaining ring threading the springs and members and engaging the posts, mechanism constructed and arranged to lock the driven shaft against rotation while the driving shaft is rotating,

and means for releasing thevsaid mechanism from` locking position.

11. In impulse starting mechanism, driving and driven shafts, a disk fast on the driving shaft and having a releasing cam,

an impelling spring carried by said disk and forming a unitary structure therewith, a pressure-applying member fast with the driven shaft and adapted to stress the spring upon relative angular displacement of the shafts, and. mechanism for locking the pressure-applying member against while the driving shaft is rotating, said 'mechanism being released by the releasing cam when the driving'amjl driven shafts have a predetermined angular displacement.

12. In impulse starting mechanism, a unitary driving element comprising a shaft, a disk fast on said shaft and having anchorage posts on its face and a cam portion on its'periphery, circularly-disposed coiled impelling and buffer springs abutting said posts, pressure-applying members extending between the impelling and buffer springs, and a retaining ring threading said springs, posts and members; a driven shaft; and mechanism for locking the pressureapplying members and (,he driven shaft against rotation while the driving shaft is rotating. said cam portion being engageable with said mechanism to release it from locking position.

11i. ln impulse starting mechanism, driv' ing and driven shafts, an impelling spring connected to the driving shaft, a disk fast on the driven shaft and having a flange with a slot and a cam portion, a pressureapplying member extending through said rotation slot and adapted to stress the spring upon relative angular displacement of the shafts, a locking member for locking the driven shaft against rotation while the driving, member is rotating. and a releasing member for releasing the locking member.

14. ln impulse starting mechanism, driving and driven shafts, a disk fast on the driving shaft and having a releasin cam portion, an impelling spring carried y the disk, a disk fast on the driven shaft and having a fiange with a slot therein, a pres-- sure-applying member extending between sections of the impelling spring and projezting through said slot, and a pawl engageable with the projecting end of said member to lock the driven shaft against rotation while the driving shaft is rotating and thereby stress the spring, said releasing cam portion being arranged to disengage thev paivl from the pressure-applying member.

15. ln impulse starting mechanism, driving and driven shafts, a disk fast on the driving shaft and having diametrically-disposed releasing cam portlons, impelling and buffer springs carried by the disk, a disk fast on the driven shaft and having a fiange with diametrically-disposed slots therein, pressure-applying members extending between the impelling and buffer springs and projecting through said slots, and a pawl adapted to engage the projecting end of either of said members to lock the driven shaft against rotation while the driven shaft is rotating and therebyl stress the impelling springs, said ram portion being arranged to disengage the pawl from respective ones of the pressure-applying members.

le. In impulse starting mechanism, driving and driven shafts, a disk fast on the driving shaft and having diametrically-disposed reieasing cam portions, impelling and buffer springs carried by the disk, a disk fast on the driven shaft and having a flange with iliametrically-disposed slots therein and a rum portion leading the slot in the direction of rotation, pressure-applying members extending between the impelling and buffer-springs and projecting throu h said slots, and a pawl adapted to engage t e projecting end of either of said members to lock the driven shaft against rotation while the driven shaft is rotating and thereby stress the impelling springs, said releasing cam portions being arranged to disengage the pawl from respective onesof the pressure-applying members. l

17. ln impulse starting mechanism, driving and driven shafts, a disk fast on the driving shaft and having a releasing cam portion, an impelling spring carried by the disk, a disk fast on the driven shaft and having a fiange with a slot therein and ram portions each leading the nearer slot in the direction of rotation, a pressure-aplUU limiting pri-.sslProapplynig arm fast with the driven plying member extending between sections oi the impelling spring and projecting through said slot, and a paWi engageable with the projecting end of said member to lock the driven shaft against rotation While the driving shaft is rotating and thereby stress the spring, said releasing cam portion being arranged to disengage the paivl from the pressureapplying member.

1&5. in impulse starting mechanism, a driving shaft, a driven shaft, an impeiling spring connected to the driving shaft, a cam fast on the driven shaft, a

shaft and adapted to stress the spring upon 'relative angular displacement ot' the shafts,

a lockingmember engageable with the pres- :uu-eapplying arm to ioek the driven shaft against rotation while the driving shat't is rotating, and a releasing cam fast on the driving shaft to disengage the loekingmember from the j)rossiireapplying arm. the pressurempplying arm trailing the limiting ram and leading the releasing can] in the direi-tion nt rotation.

l5). In `impulse starting mechanism, a driving shaft. a dri von shai't. a member fast with the driving shaft. an impelling spring arranged to be stressed upon relative anguiai' displacement ut' the shafts. locking nua'hanism for lovking the driven shaft against rotation while the driving shaft is wanting` and augularlv adjustable reichsiug moans carried by said member for ri leasing the iorkiug mechanism at the angular displacement oi the shafts predetermined by the setting oifthe releasing meiins.

iti). iu impulse starting mechanism, a

shaft, a driven shaft, a disk fast with t e drivingr shaft, an impelling spring arranged to be stressed upon relative an ular displacement of the shafts, looking mechanism tor locking .the driven shaft against rotation While the driving shaft is rotatin and a cam angularly adjustable on the dis to release the locking mechanism at the angular displacement of the shafts predetermined by the setting of the adjustable cam. O

2l. In impulse startin mechanism, a driving shaft, a driven slaft, a disk fast with the driving shaft, an. impellingspring arranged to be stressed upon relative an ular displacement of the shafts, locking mechanism for locking the driven shaft against rotation at more than one angular position, and cams carried by said disk and being arranged to release the locking mechanism when the driven shaft is at the respective locked positions, said cams being rigidly connected for likemngular adjustment relatively to said disk.

22. In impulse starting mechanism, a driving shaft, a driven shaft, a disk fast with the driving shaft,` an impelling spring arranged to be stressed upon relative anofular displacement of the shafts, lookin mechanism for locking the driven sha t against rotation at more than one angular position, a plate loosely journaled in the driving shaft and having releasing cams for rxlcasing the locking mechanism, and means for fastening said plate to said disk at angularly adjusted positions.

lu testimony whereof I affix my signature.

FREDERICK BRAKE NORIAN.

drivin 

